42 research outputs found
Discovering microbiota and volatile compounds of surströmming, the traditional Swedish sour herring
none13noIn this study, the microbiota of ready-to-eat surströmming from three Swedish producers were studied using a combined approach. The pH values of the samples ranged between 6.67±0.01 and 6.98±0.01, whereas their aw values were between 0.911±0.001 and 0.940±0.001. The acetic acid concentration was between 0.289±0.009 g/100 g and 0.556±0.036 g/100 g. Very low concentrations of lactic acid were measured. Viable counting revealed the presence of mesophilic aerobes, mesophilic lactobacilli and lactococci as well as halophilic lactobacilli and lactococci, coagulase-negative staphylococci, halophilic aerobes and anaerobes. Negligible counts for Enterobacteriaceae, Pseudomonadaceae and total eumycetes were observed, whereas no sulfite-reducing anaerobes were detected. Listeria monocytogenes and Salmonella spp. were absent in all samples. Multiplex real-time PCR revealed the absence of the bont/A, bont/B, bont/E, bont/F, and 4gyrB (CP) genes, which encode botulinic toxins, in all the samples analyzed. Metagenomic sequencing revealed the presence of a core microbiota dominated by Halanaerobium praevalens, Alkalibacterium gilvum, Carnobacterium, Tetragenococcus halophilus, Clostridiisalibacter, and Porphyromonadaceae. Psychrobacter celer, Ruminococcaceae, Marinilactibacillus psychrotolerans, Streptococcus infantis and Salinivibrio costicola were detected as minority OTUs. GC-MS analysis of volatile components revealed the massive presence of trimethylamine and sulfur compounds. Moreover, 1,2,4-trithiolane, phenols, ketones, aldehydes, alcohols, esters and long chain aliphatic hydrocarbons were also detected. The data obtained allowed pro-technological bacteria, which are well-adapted to saline environments, to be discovered for the first time. Further analyses are needed to better clarify the extent of the contribution of either the microbiota or autolytic enzymes of the fish flesh in the aroma definition.restrictedLuca Belleggia, Lucia Aquilanti, Ilario Ferrocino, Vesna Milanović, Cristiana Garofalo, Francesca Clementi, Luca Cocolin, Massimo Mozzon, Roberta Foligni, M. Naceur Haouet, Stefania Scuota, Marisa Framboas, Andrea OsimaniBelleggia, Luca; Aquilanti, Lucia; Ferrocino, Ilario; Milanovic, Vesna; Garofalo, Cristiana; Clementi, Francesca; Cocolin, Luca; Mozzon, Massimo; Foligni, Roberta; Naceur Haouet, M.; Scuota, Stefania; Framboas, Marisa; Osimani, Andre
The Microbial Diversity of Non-Korean Kimchi as Revealed by Viable Counting and Metataxonomic Sequencing
Kimchi is recognized worldwide as the flagship food of Korea. To date, most of the currently
available microbiological studies on kimchi deal with Korean manufactures. Moreover, there is a
lack of knowledge on the occurrence of eumycetes in kimchi. Given these premises, the present
study was aimed at investigating the bacterial and fungal dynamics occurring during the natural
fermentation of an artisan non-Korean kimchi manufacture. Lactic acid bacteria were dominant, while
Enterobacteriaceae, Pseudomonadaceae, and yeasts progressively decreased during fermentation.
Erwinia spp., Pseudomonas veronii, Pseudomonas viridiflava, Rahnella aquatilis, and Sphingomonas spp.
were detected during the first 15 days of fermentation, whereas the last fermentation phase was
dominated by Leuconostoc kimchi, together withWeissella soli. For the mycobiota at the beginning of the
fermentation process, Rhizoplaca and Pichia orientalis were the dominant Operational Taxonomic Units
(OTUs) in batch 1, whereas in batch 2 Protomyces inundatus prevailed. In the last stage of fermentation,
Saccharomyces cerevisiae, Candida sake, Penicillium, and Malassezia were the most abundant taxa in
both analyzed batches. The knowledge gained in the present study represents a step forward in
the description of the microbial dynamics of kimchi produced outside the region of origin using
local ingredients. It will also serve as a starting point for further isolation of kimchi-adapted
microorganisms to be assayed as potential starters for the manufacturing of novel vegetable preserves
with high quality and functional traits
Harmonic oscillator with nonzero minimal uncertainties in both position and momentum in a SUSYQM framework
In the context of a two-parameter deformation of the
canonical commutation relation leading to nonzero minimal uncertainties in both
position and momentum, the harmonic oscillator spectrum and eigenvectors are
determined by using techniques of supersymmetric quantum mechanics combined
with shape invariance under parameter scaling. The resulting supersymmetric
partner Hamiltonians correspond to different masses and frequencies. The
exponential spectrum is proved to reduce to a previously found quadratic
spectrum whenever one of the parameters , vanishes, in which
case shape invariance under parameter translation occurs. In the special case
where , the oscillator Hamiltonian is shown to coincide
with that of the q-deformed oscillator with and its eigenvectors are
therefore --boson states. In the general case where , the eigenvectors are constructed as linear combinations of
--boson states by resorting to a Bargmann representation of the latter
and to -differential calculus. They are finally expressed in terms of a
-exponential and little -Jacobi polynomials.Comment: LaTeX, 24 pages, no figure, minor changes, additional references,
final version to be published in JP
Deformed shape invariance and exactly solvable Hamiltonians with position-dependent effective mass
Known shape-invariant potentials for the constant-mass Schrodinger equation
are taken as effective potentials in a position-dependent effective mass (PDEM)
one. The corresponding shape-invariance condition turns out to be deformed. Its
solvability imposes the form of both the deformed superpotential and the PDEM.
A lot of new exactly solvable potentials associated with a PDEM background are
generated in this way. A novel and important condition restricting the
existence of bound states whenever the PDEM vanishes at an end point of the
interval is identified. In some cases, the bound-state spectrum results from a
smooth deformation of that of the conventional shape-invariant potential used
in the construction. In others, one observes a generation or suppression of
bound states, depending on the mass-parameter values. The corresponding
wavefunctions are given in terms of some deformed classical orthogonal
polynomials.Comment: 26 pages, no figure, reduced secs. 4 and 5, final version to appear
in JP
Microbial dynamics in rearing trials of Hermetia illucens larvae fed coffee silverskin and microalgae
In the present study, Hermetia illucens larvae were reared on a main rearing substrate composed of a coffee
roasting byproduct (coffee silverskin, Cs) enriched with microalgae (Schizochytrium limacinum or Isochrysis galbana)
at various substitution levels. The microbial diversity of the rearing substrates, larvae, and frass (excrement
from the larvae mixed with the substrate residue) were studied by the combination of microbial culturing on
various growth media and metataxonomic analysis (Illumina sequencing). High counts of total mesophilic aerobes,
bacterial spores, presumptive lactic acid bacteria, coagulase-positive cocci, and eumycetes were detected.
Enterobacteriaceae counts were low in the rearing diets, whereas higher counts of this microbial family were
observed in the larvae and frass. The microbiota of the rearing substrates was characterized by the presence of
lactic acid bacteria, including the genera Lactobacillus, Leuconostoc and Weissella. The microbiota of the H. illucens
larvae fed Cs was characterized by the dominance of Paenibacillus. H. illucens fed diets containing I. galbana were
characterized by the presence of Enterococcus, Lysinibacillus, Morganella, and Paenibacillus, depending on the
algae inclusion level, while H. illucens fed diets containing S. limacinum were characterized by high relative
abundances of Brevundimonas, Enterococcus, Paracoccus, and Paenibacillus, depending on the algae inclusion level.
Brevundimonas and Alcaligenes dominated in the frass from larvae fed I. galbana; the predominance of Brevundimonas
was also observed in the frass from larvae fed Schyzochitrium-enriched diets. Based on the results of
the present study, an effect of algae nutrient bioactive substances (e.g. polysaccharides, high-unsaturated fatty
acids, taurine, carotenoids) on the relative abundance of some of the bacterial taxa detected in larvae may be
hypothesized, thus opening new intriguing perspectives for the control of the entomopathogenic species and
foodborne human pathogens potentially occurring in edible insects. Further studies are needed to support this
hypothesis. Finally, new information on the microbial diversity occurring in insect frass was also obtained
Deformed algebras, position-dependent effective masses and curved spaces: An exactly solvable Coulomb problem
We show that there exist some intimate connections between three
unconventional Schr\"odinger equations based on the use of deformed canonical
commutation relations, of a position-dependent effective mass or of a curved
space, respectively. This occurs whenever a specific relation between the
deforming function, the position-dependent mass and the (diagonal) metric
tensor holds true. We illustrate these three equivalent approaches by
considering a new Coulomb problem and solving it by means of supersymmetric
quantum mechanical and shape invariance techniques. We show that in contrast
with the conventional Coulomb problem, the new one gives rise to only a finite
number of bound states.Comment: 22 pages, no figure. Archive version is already official. Published
by JPA at http://stacks.iop.org/0305-4470/37/426
The CroHort Study: Cardiovascular Behavioral Risk Factors in Adults, School Children and Adolescents, Hospitalized Coronary Heart Disease Patients, and Cardio Rehabilitation Groups in Croatia
Based on repeated measurement of health behaviors the CroHort Study showed that health behavior explains a great deal more of class inequalities in mortality than observed in previous studies. These include decreasing prevalence of smoking and increase in obesity, hypertension and diabetes mellitus. The lowest prevalence of health risks was recorded among children and adolescents, followed by general adult population from the CroHort Study. Hospitalized coronary heart disease patients had higher risks prevalence than general population, while the highest prevalence of risks was recorded among patients in cardiac rehabilitation program. The higher levels of stress were associated to lower financial
conditions, poorer social functioning and poorer mental health for bothmen and women. Higher levels of stress were also associated with heart problems, higher alcohol consumption in men while in women stress was associated to poorer general health, higher age and lower levels of education